Mold with heat regulation ducts and its realization method

ABSTRACT

A mold includes ducts designed to be traveled by heat-regulating fluid of the mold. The ducts are realized by grooves realized on the external surface of the mold and closed above along their extension by metallic strips. Advantageously the grooves are formed by pairs of ribs projecting from the surface of the mold to form side walls of the ducts.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a mold with heat-regulation ducts and to a method for its realization.

2. State of the Prior Art

In the production of metallic molds which are to be heat regulated (heated and cooled) on the surface by different heating vectors (diathermic oil, water et cetera) there are at present some technical possibilities.

A first possibility in the case that the mold is made up of a metallic block is to realize drillings at a sufficient distance from the internal surface of the mold and connect the drillings with the external tubes.

But this procedure becomes particularly complex when the surface of the mold is curved or arranged on different levels often forcing compromises among many and costly drillings or drillings which are at different distances from the internal surface of the mold with resulting variations in the surface thermal yield. In addition, this technology does not lend itself to the realization of molds which must necessarily have reduced thicknesses such as, for example, rotating molds.

A second possibility is to realize the mold by melting by inserting in the casting the heat-regulation circuit realized with tubing in a more highly melting material than that of the mold. In this manner the heat-regulation circuit is ‘co-melted’ in the mold.

But this procedure has considerable problems. For example the positioning of the piping in the seat in which the metal of the mold will be melted is a delicate operation which can easily cause defects since the metal of the piping has an expansion coefficient different from the melting metal and can cause distortions in the mold or jeopardize solidification in the melted metal to create surface defects due to shrinkage, suction, porosity et cetera. In addition, in case of errors or necessity of changing, the intervention operation becomes much more complex and makes it necessary to intervene on two co-melted metals. Lastly, the heat conductivity of the mold is reduced and in general conditioned by the presence of a piping system of material different from that of the mold.

A third known possibility is to realize the mold as a metallic shell going to screw onto the rear thereof another metallic shell which is often a welded sheet metal cover realizing an air space in which to cause the heat-regulation fluid to flow.

This latter solution however has disadvantages linked to the fact that the air space, especially in the presence of curved surfaces or on different planes, may have different depths in the various zones of the mold with resulting non-uniformity of heat exchange. The presence of a single air space also forces using considerable masses of fluid with decrease of outputs and considerable increase of the weight of the molds, which becomes particularly detrimental for some molding technologies among which, for example, rotary molding.

There being no bulkheads, there is no guarantee that the fluid circulates over all of the surface of the mold instead of following preferential circuits and thus generating different surface heat yields.

Lastly these molds over time often have problems of sealing between the surface shell and the cover.

The general purpose of the present invention is to remedy the above mentioned shortcomings by making available a method for the realization of a mold with heat-regulation channels allowing obtaining a heat-regulated mold in a simple and effective manner without the disadvantages of the known art.

SUMMARY OF THE INVENTION

In view of this purpose it was sought to provide in accordance with the present invention a mold including ducts designed to be paths for heat-regulating fluid of the mold and characterized in that the ducts are realized by grooves on the external surface of the mold closed above along their extension by metallic strips.

Again in accordance with this invention it was sought to realize a mold realization method with ducts designed to be run through by heat-regulation fluid of the mold including the steps of realization on the external surface of the mold of a plurality of grooves identifying channels open above and then fasten thereon along their extension metallic strips to constitute top closing of the channel to form a duct.

BRIEF DESCRIPTION OF THE DRAWINGS

To clarify the explanation of the innovative principles of the present invention and its advantages compared with the prior art there is described below with the aid of the annexed drawings a possible embodiment thereof by way of non-limiting example applying said principles. In the drawings:

FIG. 1 shows a partially exploded diagrammatic perspective view of part of a mold realized in accordance with this invention,

FIG. 2 shows shaped sheet metal parts used in the mold of FIG. 1, and

FIG. 3 shows a cross section view of a heat-regulation channel of the mold of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the figures, FIG. 1 shows diagrammatically a mold designated as a whole by reference number 10 and advantageously for rotary molding realized in accordance with this invention.

The mold 10 includes a mold body 11 (with interior reproducing the shape to be got) on the external surface of which there are grooves 16 for forming channels open on the top. Advantageously the grooves are formed laterally by ribs 12 placed at an appropriate distance apart and projecting from the external surface of the mold to form the side surfaces of the channels.

The channel grooves or ribs can be obtained by mechanical removal of material or directly as melting of the mold body. This can also be done to conform to the technique of realization of the metal mold shell which as for the side walls of the heat-regulation system can be conveniently realized by mechanical processing from a metallic block or by melting. It can be of aluminum.

Each channel is closed in segments by metallic strips welded between the ribs. Advantageously the strips include straight sheet metal bands 13 in the straight sections (cut from a ribbon and possible bent) and from curves of sheet metal handlebar 14 (advantageously cut from a metal sheet), welded over the pairs of ribs which realize the channel sides. The channels end in unions 17 for connection of known means (not shown) for circulation of the heat-regulation fluids (heating and cooling). The material of the bands and curves of suitable thickness can be the same as the ribs. The unions between one strip segment and the other can also be obtained advantageously by welding.

FIG. 2 shows as an example the cutting of all the sheet metal curves 14 necessary for realization of the channels of the mold of FIG. 1.

FIG. 3 shows as an example the section of a channeling (designated by 15) made up of side ribs 12 between which a band 13 is welded.

Advantageously the ribs have a height from the mold surface greater that the thickness (in particular at least double) and also have thickness which is less (in particular at least half) the distance between two ribs forming the walls of a same channel. This allows optimization of their efficiency in the heat exchange.

It is now clear how the preset purposes of this invention have been achieved by making available a channeled mold and a method for its realization.

The advantages obtained by applying this invention are for example the capability of realizing lighter molds than those obtained from the block by drilling and the capability of easily realizing any heat-regulation path even on complex surfaces while also ensuring a constant distance of the latter from the internal surface of the mold. In addition, thanks to the use of this invention, the mold and the heat-regulation circuit can by easily made of the same material with resulting advantages due to the homogeneousness of heat conduction. In a mold channeled in accordance with this invention there is better heat exchange between heat-regulation fluid and the metal of the mold. For example the heat conductivity of the mold is not reduced and, in general, is not conditioned by the presence of piping of material different from that of the mold as happens in known molds equipped with piping incorporated in the melting. There is also a considerable ease of intervention for modification, the mold and the heat-regulation system being realized of the same material and the surface of the channels being easily accessible.

Naturally the above description of an embodiment applying the innovative principles of the present invention is given by way of non-limiting example of said principles within the scope of the exclusive right claimed here. For example, the mold and the channels could have another course than that shown as an example depending of the specific practical requirements. 

1. Mold including ducts designed to be run through by heat-regulating fluid of the mold and characterized in that the ducts are realized by grooves on the external surface of the mold closed above along their extension by metallic strips.
 2. Mold in accordance with claim 1 characterized in that the grooves are identified laterally by pairs of ribs projecting from the external surface of the mold and on the top of which are fastened the metallic strips.
 3. Mold in accordance with claim 1 characterized in that the metallic strips are welded.
 4. Mold in accordance with claim 1 characterized in that the strips are formed in segments along the extension of the ducts and that the segments include sheet metal bands cut from strip and sheet metal curves cut from a sheet.
 5. Mold in accordance with claim 1 characterized in that the grooves are made in melting from the mold body.
 6. Mold in accordance with claim 1 characterized in that the grooves are made by removal of material from the mold body.
 7. Mold in accordance with claim 1 characterized in that the strips are of the same material as the external surface of the mold.
 8. Mold in accordance with claim 2 characterized in that the height of the ribs above the surface of the mold is greater than the thickness.
 9. Mold in accordance with claim 2 characterized in that the thickness of the ribs is less than the distance between two ribs forming the walls of a same channel.
 10. Mold in accordance with claim 1 characterized in that the grooves end in unions for connection to a fluid supply.
 11. Method for realization of a mold with ducts designed to be traveled by heat-regulation fluid of the mold and including the steps of realization on the external surface of the mold of a plurality of grooves identifying channels open above and then fastening onto the latter along their extension metallic strips to constitute upper closing of the channel to form a duct.
 12. Method in accordance with claim 11 in which the grooves are identified laterally by pairs of ribs projecting from the external surface of the mold and on the top of which are fastened the metallic strips.
 13. Method in accordance with claim 11 in which the metallic strips are fastened by welding.
 14. Method in accordance with claim 11 in which the strips are formed as segments along the extensions of the channels and the segments include sheet metal strips which are cut from ribbon and sheet metal curves which are cut from a sheet.
 15. Method in accordance with claim 11 in which the grooves are made in melting from the mold body.
 16. Method in accordance with claim 11 in which the grooves are made by removal of material from the mold body. 